Symbiosis

Ryan Fernandes

Symbiosis

• Is two or more species that live intimately together. – i.e. their fates are linked

• Why bother? – Increases chances of survival

Symbiosis

• Types of symbiosis – Mutualism – Commensalism – Parasitism

• Who is involved? – The host: usually the LARGER of the two and what

the symbiont is using to live. – The symbiont: usually the SMALLER of the two

and what is living off of another organism.

Symbiosis - Mutualism

• Both symbiont and host get a benefit. – Also called “win-win” – +/+

• This can be a long-term or short-term relationship.

• Can be very important in evolution – If something wipes out one of the two, then it

could mean the other will have to adapt or go extinct too.

Symbiosis - Mutualism

• Example: Bees and flowers - How is this mutualism? - What happens when something happens to the bees? - What happens if the

flowers disappear?

Symbiosis - Parasitism

• The host is harmed and the symbiont gains something. – A “win-lose” situation – +/-

• Different than predation because death is not immediate. – Also because symbiont cannot survive without

host.

Symbiosis - Parasitism

• Example: Ticks deer - Would ticks survive without deer? - Would deer evolution change? - What harm is caused?

Symbiosis – Commensalism

• Symbiont is helped and there is no cost for the host. – Just a win for the symbiont. – +/0

• The benefits are only for the symbiont. – There can be no benefit or cost to the host.

Symbiosis - Commensalism

• Example: Barnacles on whales - Is there any benefit to

the whale? - What about barnacle? - Would whale evolution

be different or the same if barnacle disappeared?

Symbiosis - Commensalism

• Can there ever be true commensalism?

Symbiosis – Commenalism

Symbiosis – Commensalism

• How much harm is to much?

Symbiosis